<?php

# KCAPTCHA PROJECT VERSION 2.0

# Automatic test to tell computers and humans apart

# Copyright by Kruglov Sergei, 2006, 2007, 2008, 2011
# www.captcha.ru, www.kruglov.ru

# System requirements: PHP 4.0.6+ w/ GD

# KCAPTCHA is a free software. You can freely use it for developing own site or software.
# If you use this software as a part of own sofware, you must leave copyright notices intact or add KCAPTCHA copyright notices to own.
# As a default configuration, KCAPTCHA has a small credits text at bottom of CAPTCHA image.
# You can remove it, but I would be pleased if you left it. ;)

class KCAPTCHA{

   # generates keystring and image
   function KCAPTCHA(){

# KCAPTCHA configuration file

$alphabet = "0123456789abcdefghijklmnopqrstuvwxyz"; # do not change without changing font files!

# symbols used to draw CAPTCHA
$allowed_symbols = "23456789abcdegikpqsvxyz"; #alphabet without similar symbols (o=0, 1=l, i=j, t=f)

# folder with fonts
$fontsdir = 'images/captcha';   

# CAPTCHA string length
$length = mt_rand(6,7); # random 4 or 5 or 6 or 7

# CAPTCHA image size (you do not need to change it, this parameters is optimal)
$width = 173;
$height = 83;

# symbol's vertical fluctuation amplitude
$fluctuation_amplitude = 8;

#noise
$white_noise_density=1/6;
$black_noise_density=1/30;

# increase safety by prevention of spaces between symbols
$no_spaces = true;

# show credits
$show_credits = true; # set to false to remove credits line. Credits adds 12 pixels to image height
$credits = ''; # if empty, HTTP_HOST will be shown

# CAPTCHA image colors (RGB, 0-255)
$foreground_color = array(mt_rand(0,80), mt_rand(0,80), mt_rand(0,80));
$background_color = array(mt_rand(220,255), mt_rand(220,255), mt_rand(220,255));

# JPEG quality of CAPTCHA image (bigger is better quality, but larger file size)
$jpeg_quality = 100;
      $fonts=array();
      $fontsdir_absolute=dirname(__FILE__).'/'.$fontsdir;
      if ($handle = opendir($fontsdir_absolute)) {
         while (false !== ($file = readdir($handle))) {
            if (preg_match('/\.png$/i', $file)) {
               $fonts[]=$fontsdir_absolute.'/'.$file;
            }
         }
          closedir($handle);
      }   
   
      $alphabet_length=strlen($alphabet);
      
      do{
         // generating random keystring
         while(true){
            $this->keystring='';
            for($i=0;$i<$length;$i++){
               $this->keystring.=$allowed_symbols{mt_rand(0,strlen($allowed_symbols)-1)};
            }
            if(!preg_match('/cp|cb|ck|c6|c9|rn|rm|mm|co|do|cl|db|qp|qb|dp|ww/', $this->keystring)) break;
         }
      
         $font_file=$fonts[mt_rand(0, count($fonts)-1)];
         $font=imagecreatefrompng($font_file);
         imagealphablending($font, true);

         $fontfile_width=imagesx($font);
         $fontfile_height=imagesy($font)-1;
         
         $font_metrics=array();
         $symbol=0;
         $reading_symbol=false;

         // loading font
         for($i=0;$i<$fontfile_width && $symbol<$alphabet_length;$i++){
            $transparent = (imagecolorat($font, $i, 0) >> 24) == 127;

            if(!$reading_symbol && !$transparent){
               $font_metrics[$alphabet{$symbol}]=array('start'=>$i);
               $reading_symbol=true;
               continue;
            }

            if($reading_symbol && $transparent){
               $font_metrics[$alphabet{$symbol}]['end']=$i;
               $reading_symbol=false;
               $symbol++;
               continue;
            }
         }

         $img=imagecreatetruecolor($width, $height);
         imagealphablending($img, true);
         $white=imagecolorallocate($img, 255, 255, 255);
         $black=imagecolorallocate($img, 0, 0, 0);

         imagefilledrectangle($img, 0, 0, $width-1, $height-1, $white);

         // draw text
         $x=1;
         $odd=mt_rand(0,1);
         if($odd==0) $odd=-1;
         for($i=0;$i<$length;$i++){
            $m=$font_metrics[$this->keystring{$i}];

            $y=(($i%2)*$fluctuation_amplitude - $fluctuation_amplitude/2)*$odd
               + mt_rand(-round($fluctuation_amplitude/3), round($fluctuation_amplitude/3))
               + ($height-$fontfile_height)/2;

            if($no_spaces){
               $shift=0;
               if($i>0){
                  $shift=10000;
                  for($sy=3;$sy<$fontfile_height-10;$sy+=1){
                     for($sx=$m['start']-1;$sx<$m['end'];$sx+=1){
                          $rgb=imagecolorat($font, $sx, $sy);
                          $opacity=$rgb>>24;
                        if($opacity<127){
                           $left=$sx-$m['start']+$x;
                           $py=$sy+$y;
                           if($py>$height) break;
                           for($px=min($left,$width-1);$px>$left-200 && $px>=0;$px-=1){
                                $color=imagecolorat($img, $px, $py) & 0xff;
                              if($color+$opacity<170){ // 170 - threshold
                                 if($shift>$left-$px){
                                    $shift=$left-$px;
                                 }
                                 break;
                              }
                           }
                           break;
                        }
                     }
                  }
                  if($shift==10000){
                     $shift=mt_rand(4,6);
                  }

               }
            }else{
               $shift=1;
            }
            imagecopy($img, $font, $x-$shift, $y, $m['start'], 1, $m['end']-$m['start'], $fontfile_height);
            $x+=$m['end']-$m['start']-$shift;
         }
      }while($x>=$width-20); // while not fit in canvas

      //noise
      $white=imagecolorallocate($font, 255, 255, 255);
      $black=imagecolorallocate($font, 0, 0, 0);
      for($i=0;$i<(($height-60)*$x)*$white_noise_density;$i++){
         imagesetpixel($img, mt_rand(0, $x-1), mt_rand(10, $height-30), $white);
      }
      for($i=0;$i<(($height-60)*$x)*$black_noise_density;$i++){
         imagesetpixel($img, mt_rand(0, $x-1), mt_rand(10, $height-30), $black);
      }

      
      $center=$x/2;

      // credits. To remove, see configuration file
      $img2=imagecreatetruecolor($width, $height+($show_credits?12:0));
      $foreground=imagecolorallocate($img2, $foreground_color[0], $foreground_color[1], $foreground_color[2]);
      $background=imagecolorallocate($img2, $background_color[0], $background_color[1], $background_color[2]);
      imagefilledrectangle($img2, 0, 0, $width-1, $height-1, $background);      
      imagefilledrectangle($img2, 0, $height, $width-1, $height+12, $foreground);
      $credits=empty($credits)?$_SERVER['HTTP_HOST']:$credits;
      imagestring($img2, 2, $width/2-imagefontwidth(2)*strlen($credits)/2, $height-2, $credits, $background);

      // periods
      $rand1=mt_rand(750000,1200000)/10000000;
      $rand2=mt_rand(750000,1200000)/10000000;
      $rand3=mt_rand(750000,1200000)/10000000;
      $rand4=mt_rand(750000,1200000)/10000000;
      // phases
      $rand5=mt_rand(0,31415926)/10000000;
      $rand6=mt_rand(0,31415926)/10000000;
      $rand7=mt_rand(0,31415926)/10000000;
      $rand8=mt_rand(0,31415926)/10000000;
      // amplitudes
      $rand9=mt_rand(330,420)/110;
      $rand10=mt_rand(330,450)/100;

      //wave distortion

      for($x=0;$x<$width;$x++){
         for($y=0;$y<$height;$y++){
            $sx=$x+(sin($x*$rand1+$rand5)+sin($y*$rand3+$rand6))*$rand9-$width/2+$center+1;
            $sy=$y+(sin($x*$rand2+$rand7)+sin($y*$rand4+$rand8))*$rand10;

            if($sx<0 || $sy<0 || $sx>=$width-1 || $sy>=$height-1){
               continue;
            }else{
               $color=imagecolorat($img, $sx, $sy) & 0xFF;
               $color_x=imagecolorat($img, $sx+1, $sy) & 0xFF;
               $color_y=imagecolorat($img, $sx, $sy+1) & 0xFF;
               $color_xy=imagecolorat($img, $sx+1, $sy+1) & 0xFF;
            }

            if($color==255 && $color_x==255 && $color_y==255 && $color_xy==255){
               continue;
            }else if($color==0 && $color_x==0 && $color_y==0 && $color_xy==0){
               $newred=$foreground_color[0];
               $newgreen=$foreground_color[1];
               $newblue=$foreground_color[2];
            }else{
               $frsx=$sx-floor($sx);
               $frsy=$sy-floor($sy);
               $frsx1=1-$frsx;
               $frsy1=1-$frsy;

               $newcolor=(
                  $color*$frsx1*$frsy1+
                  $color_x*$frsx*$frsy1+
                  $color_y*$frsx1*$frsy+
                  $color_xy*$frsx*$frsy);

               if($newcolor>255) $newcolor=255;
               $newcolor=$newcolor/255;
               $newcolor0=1-$newcolor;

               $newred=$newcolor0*$foreground_color[0]+$newcolor*$background_color[0];
               $newgreen=$newcolor0*$foreground_color[1]+$newcolor*$background_color[1];
               $newblue=$newcolor0*$foreground_color[2]+$newcolor*$background_color[2];
            }

            imagesetpixel($img2, $x, $y, imagecolorallocate($img2, $newred, $newgreen, $newblue));
         }
      }
      
      header('Expires: Mon, 26 Jul 1997 05:00:00 GMT'); 
      header('Cache-Control: no-store, no-cache, must-revalidate'); 
      header('Cache-Control: post-check=0, pre-check=0', FALSE); 
      header('Pragma: no-cache');
      if(function_exists("imagejpeg")){
         header("Content-Type: image/jpeg");
         imagejpeg($img2, null, $jpeg_quality);
      }else if(function_exists("imagegif")){
         header("Content-Type: image/gif");
         imagegif($img2);
      }else if(function_exists("imagepng")){
         header("Content-Type: image/x-png");
         imagepng($img2);
      }
   }

   // returns keystring
   function getKeyString(){
      return $this->keystring;
   }
}
session_name('SESID');
session_start();
$captcha = new KCAPTCHA();
$_SESSION['code'] = $captcha->getKeyString();
?>